This invention relates to an audibly announcing apparatus, and more particularly to power supply control circuitry with power saving features for use in an audibly announcing apparatus.
Recently, new types of devices which provide information in the form of audible sounds or synthesized voices have been developed; for example, a talking watch that provides audible sounds indicative of updated time and a talking calculator that performs arithemetic operations on keyed information and provides the results of the arithmetic operations in the form of audible sounds or voices. The use of a recording medium such as a magnetic tape storing a given number of phenomes in the form of analog signals and a speech synthesis method which relies upon a semiconductor memory or like for storing digitally encoded phoneme data and a digital-to-analog converter are widely known ways of converting numerical information and time information.
However, the circuitry which ultimately converts such numerical information or time information (hereinafter referred to as "voice control circuit") tends to consume a relatively great amount of power as compared with the internal circuitry of the audibly announcing apparatus including a timekeeping circuit and a calculation circuit. This is due to the fact that the recording medium control needs some mechanical controls and the speech synthesis method must process arithmetic operations at high speed. It is universally appreciated that the higher the processing speed the greater power consumption.